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Luisa Aires, Pedro Silva, Gustavo Silva, Maria Paula Santos, José Carlos Ribeiro and Jorge Mota

Background:

The purpose of this study was to analyze the relation between body mass index (BMI), Cardiorespiratory Fitness (CRF), and levels of physical activity (PA) from sedentary to very vigorous intensities, measured by accelerometry, in students from a middle and high school.

Methods:

This cross-sectional study included 111 children and adolescents, age 11 to 18 years. PA was assessed with an accelerometer for 7 consecutive days (1 minute epoch) using specific cut-points. PA components were derived using special written software (MAHUffe). CRF was assessed by maximal multistage 20m shuttle run. T-test was used to test differences between BMI groups, Pearson’s correlation, to analyze correlations between all variables and multinomial logistic regression, and to predict the value of BMI categories.

Results:

This paper provides evidence that BMI was inversely and significantly correlated with CRF. Only CRF was correlated with Vigorous and Very Vigorous PA levels and total amount of PA. Children with Overweight/Obesity were less likely to perform more laps than normal weight counterparts. The total amount or intensity level of PA did not show any influence on BMI level.

Conclusions:

Low CRF is strongly associated with obesity, which highlights the importance of increasing CRF for a protective effect even in youth. No associations were found for PA and BMI.

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Luisa Aires, Michael Pratt, Felipe Lobelo, Rute Marina Santos, Maria Paula Santos and Jorge Mota

Background:

The objective of this study was to analyze associations of cardiorespiratory fitness (CRF) with physical activity, time spent watching television and using computer, mode of commuting to school (CS), and adiposity, by gender.

Methods:

Participants were 1708 students (53.8% girls), aged 11 to 19 years. CRF was evaluated with a 20-meter shuttle-run test using VO2max by previously published equation. Maturation stages determined by Tanner’s criteria, body mass index, and skinfolds were measured, and a questionnaire used to assess socioeconomic status, PA, television and computer time, and mode of CS. We conducted a regression analysis using CRF as the dependent variable.

Results:

CRF was independent and positively associated with physical activity [β = 0.338 (95% CI = 0.119; 0.188); P < .001] and with maturation [β = −0.876 (95% CI = 0.666; 1.087); P < .001]; independent and negatively associated with television time [β = −0.003 (95% CI = −0.005; −0.002); P < .001] and adiposity [β = −0.068 (95% CI = −0.076; −0.060); P < .001]. CRF was positively associated with CS [β = 0.337; (95% CI = 0.014; 0.741); P = .014]. No associations were found for computer time.

Conclusions:

These findings suggest that increasing overall physical activity levels through interventions in different domains such as active CS, reducing sedentary activities, such as television time, might be effective strategies for improving CRF in youth.

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Jorge Mota, Rute M. Santos, Pedro Silva, Luisa Aires, Clarice Martins and Susana Vale

Background:

The main goal of this study was to analyze the associations between cardiorespiratory fitness (CRF) and body mass index (BMI) with self-rated health (SRH) of adolescent girls.

Methods:

This was a cross-sectional study of 533 adolescents girls, aged from 10 to 18 years old. CRF was predicted by maximal multistage 20-m shuttle-run test according to procedures described from FITNESSGRAM. Girls’ obesity status was classified according to International Obesity Task Force and Self-rated health (SRH) was assessed by questionnaire.

Results:

The findings showed that among adolescent girls 23.2% had negative SRH. Girls who were classified as unfit were more likely to report negative SRH in both univariate logistic (OR: 3.05; CI: 1.91−4.87; P < .05) and multivariate (OR: 2.93; CI: 1.82−4.72; P < .05) regression analyses compared with their fit peers. Obese girls were more likely to report negative SRH (OR: 2.30; CI: 1.14−4.62; P < .05) compared with their normal-weight counterparts. However such association was lost in multivariate analyses suggesting an effect of CRF.

Conclusions:

Negative perception of health was associated with lower CRF and weight status although such association it is mediated by CRF condition.

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Jorge Mota, Pedro Silva, Luísa Aires, Maria Paula Santos, José Oliveira and José C. Ribeiro

Background:

The purpose of this study was to examine whether there are differences in physical activity (PA) during specific periods of the day among active and less-active girls.

Methods:

The sample comprised 54 girls age 10 to 15 years. PA was assessed by accelerometry. Girls were grouped as less active, active, and highly active.

Results:

Total minutes of moderate-to-vigorous physical activity (MVPA) was significantly higher in more-active girls than in their less-active peers (113 and 72 min/d, respectively). The most-active groups were significantly more engaged in MVPA during the outside-of-school period than were less-active girls. Highly active girls spent a significantly higher amount of their MVPA time outside of school than did the less-active group, which spent a significantly higher proportion of MVPA time during late afternoon.

Conclusion:

Outside-of-school PA is a key point for MVPA engagement. Particularly for the less-active girls, however, schools might provide additional PA.

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Gustavo Silva, Luísa Aires, Jorge Mota, José Oliveira and José Carlos Ribeiro

The purpose of this study was to calculate and validate reference standards for the 20-m shuttle run test (SR) in youths aged 10–18 years. Reference standards based on the number of completed SR laps were calculated by LMS method in a reference group of 5559 students. Cut-off values for SR laps were determined and tested by ROC curve analysis in a validation group (633 students), from which waist circumference, HDL-cholesterol, triglycerides, fasting glucose and mean arterial pressure were assessed to calculate a metabolic risk score, later dichotomized in low and high metabolic risk (HMRS). The accuracy of SR laps standards was significant for girls (AUC = 0.66; 95% CI = 0.58–0.74; p < .001) and boys (AUC = 0.71; 95% CI = 0.62–0.79; p < .001) for identifying subjects at HMRS. The 40th percentile was the best cut-off for SR laps in girls (SENS = 0.569; 1-SPEC = 0.330) and boys (SENS = 0.634; 1-SPEC = 0.266). New SR laps reference standards are able to discriminate metabolic risk levels, and may provide a valuable tool for early prevention of cardiovascular risk factors.

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Pedro Silva, Luisa Aires, Rute Marina Santos, Susana Vale, Greg Welk and Jorge Mota

Background:

The purpose of the study is to evaluate age and gender differences in objectively measured levels of physical activity (PA) in a large and diverse sample of residents from an urban area in Porto, Portugal.

Methods:

Participants included 822 residents, 334 males (41%), and 488 females (59%), aged 6 to 90 years. GT1M accelerometer was used to assess daily PA over 7 consecutive days, and the measurement was from October (2007) to June (2008).

Results:

Males were more active than females. This difference was attenuated in the 2 oldest age groups (40−59 and 60+ yrs). An accentuated declined in all PA variables occurred between the youngster group (6−11 yrs) and adolescents group (12−19 yrs). Surprisingly, young adults (20−39 yrs) engaged in more moderate-to-vigorous PA (MVPA) than adolescents. Further, females also had higher MVPA in the fourth group (40−59 yrs) compared with the second group (12−19 yrs). Males had higher compliance rates of PA guidelines than females regardless the age group considered. Adolescents had very low compliance rates (females = 18.18%; males = 33.50%).

Conclusions:

Porto metropolitan area residents had low rates of compliance with current PA guidelines. A low level of PA in Porto adolescents is a matter of concern and suggests that interventions are needed.

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Clarice Martins, Ismael Freitas Jr., Andréia Pizarro, Luísa Aires, Gustavo Silva, Maria Paula Santos and Jorge Mota

Nonalcoholic fatty liver disease (NAFLD) is one of the most frequent complications associated with excess adiposity. Its pathogenesis is complex and there are multiple factors that may contribute to it. AIM: To analyze whether cardiorespiratory fitness (CRF), waist circumference (WC), and C-reactive protein (CRP) are associated with alanine aminotransferase (ALT) in children with obesity. METHODS: 79 overweight/obese children of both genders, 11–13 year-olds, with abnormal serum ALT from Porto public schools comprised the sample. Measurements included CRF (20-m Shuttle Run Test), WC (NHANES protocol), CRP and ALT (Cholestech LDX analyzer). Logistic regression adjusted for gender, maturation, and weight with ALT levels as dependent variable (risk vs. non risk), and WC (risk vs. non risk), CRP (risk vs. non risk), and CRF (fit vs. unfit) as independent variables. Level of significance was set at 95%. RESULTS: Logistic regression showed that obese fit children were less likely to have abnormal ALT values (OR=.031) CONCLUSION: In obese children, higher cardiovascular fitness appears to reduce the chance of decreased liver function.

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Henrique Nascimento, Ana Inês Alves, Ana Filipa Medeiros, Susana Coimbra, Cristina Catarino, Elsa Bronze-da-Rocha, Elísio Costa, Petronila Rocha-Pereira, Gustavo Silva, Luísa Aires, André Seabra, Jorge Mota, Helena Ferreira Mansilha, Carla Rêgo, Alice Santos-Silva and Luis Belo

Purpose:

There are few reliable studies assessing the effect of physical exercise (PE) on adipokines levels at young ages. Our objective was to study the effects of regular PE on plasma adipokines in pediatric overweight and obesity.

Method:

117 overweight and obese children and adolescents (47% females; 10.2 years) participated in an 8-month longitudinal study divided in two groups: PE group (n = 80), engaged in an after-school PE program; control group (n = 37), with no PE program. Plasma lipids, C-reactive protein (CRP), adiponectin, resistin, leptin, IL-6, IL-1beta, TNF-alpha, insulin and glucose levels were determined.

Results:

contrarily to the control group, the PE group presented reductions in body mass index z-score (BMIzsc) and body fat percentage that were accompanied by an improvement in lipid profile and insulin resistance, a reduction in CRP and TNF-alpha and an increase in adiponectin levels. The reductions in BMIzsc were inversely correlated with changes in adiponectin (r=−0.329, p = .003) and positively correlated with changes in percentage body fat (r = .262, p = .032), triglycerides (r = .228, p = .042) and leptin (r = .285, p = .010).

Conclusion:

Moderate reductions in adiposity improve proinflammatory status in obese children and adolescents. A more substantial reduction in BMIzsc was associated with a greater increment in adiponectin and reduction in leptin.